Energy absorbing steering column assemblies are well known in the art. Typically, such assemblies include a telescopically sectional steering column having an upper column section telescopically received about a lower column section and with there being provided an energy absorbing structure within the steering column sections, or fixed to the steering column section and supporting it to a main support bracket affixed to the vehicle body. Typical such arrangements are shown in U.S. Pat. Nos. 3,923,319, 4,102,217, 4,194,411 and 4,616,522. Additional systems are shown in U.S. Pat. Nos. 3,813,960; 4,627,306 and 4,774,299, all of which are assigned to the assignee of the present invention.
Also, it is well known in the art to provide an energy absorbing steering column assembly of the type wherein the main support bracket for the steering column is plastically deformable on being subjected to an impact load of a predetermined magnitude. Generally, amongst these disclosures, impact loads with two or more degrees of freedom or direction of travel of the steering column assembly can be absorbed through the infrastructure of the main support bracket. Typical of such disclosures are those shown in U.S. Pat. Nos. 3,785,671, 3,505,897, 3,521,724, 3,803,938 and 4,228,695.
None of the prior art devices, however, recognize the need for or provide a passive restraint load limiting column support system adapted to come into play only when the primary energy absorbing system, whatever it may be, fails to provide the energy absorbing controlled collapse of the steering column assembly as designed, or one which is adapted to come into play only upon receiving impact loads of greater magnitude than those for which the system was designed.